Treatment of organic derivatives of cellulose



Patented Aug. 6, 1935 UNITED STATES PATENT OFFICE TREATMENT OF ORGANIC DERIVATIVES F CELLULOSE Camille Dreyfus, New York, N. Y., and Herbert Platt, Cumberland, Md., assignors to Celanese Corporation of America, a corporation of Dela- This invention relates to a new and improved process for the weighting of organic esters and ethers of cellulose, more specifically cellulose ace tate. Various processes are known for weighting fabrics, fibers, etc. of such derivatives but the process of the applicants is more simple and more economical.

An object of this invention is to provide a new and economical process for the weighting of organic esters and ethers of cellulose, more specifically cellulose acetate. Another object of this invention is to provide a process for treating organic esters and ethers of cellulose with a swelling agent and a weighting agent. Still another object of this invention is to obtainimproved products of organic esters of cellulose, for example, cellulose acetate, containing compounds of metals fixed therein in insoluble form.

This process is applicable to organic deriva- 00 tives of cellulose whether they are in yarn, fiber or fabric form. It results not only in a product of greater weight and volume but also gives to the thus treated material other valuable properties. They are more resistant to heat and can, therefore, be ironed with a hotter iron than can a similar untreated material without melting the fibers. Also the infiammability of the untreated fibers, fabrics, etc. is much greater than that of the similar weighted material. The weighting of circular knitted fabrics made from such organic derivatives of cellulose has the very desirable result of considerably lessening the tendency of such a fabric to ladder (or run). Woven fabric containing organic derivatives of cellulose is also benefited by the weighting treatment since its tendency toslip or shift is materially reduced.

The advantages resulting from the applicants process of weighting are not limited to those set 40 out above. Thus it has been found that fabrics which have been weighted in accordance with this process exhibit a marked increase in strength,

, for instance in several cases it was found that the increase in the strength of the weft of the fabric was approximately percent. Similarly fabic thus treated showed greater percentage of elongation at the,breaking point than similar material untreated oi similar material which had been weighted in the usual way.

The applicants process consists, essentially, in treating organic derivatives of cellulose with a solution of stannic chloride of such concentration that it acts as a jelling agent as well as a weighting agent. The material which has thus been treated with the stannic chloride is then washed with water, a weak alkali solution or a very dilute solution of an alkaline salt. This washing serves to fix the tin in the fabric or fibers or other material treated in insoluble form, very probably, or largely, as stannic oxide. In the above process, where it is desired, the material to be weighted may first be treated with a jelling agent therefor and subsequently treated with a dilute solution of the stannic chloride as the weighting agent.

Where deemed desirable, the washing with water, alkali or alkaline salts, above referred to, can be replaced by a soaping treatment Of the material treated with stannic chloride Prererably the treated material should beiwashed with water before it is subjected toan alkali wash or a soaping treatment. The soaping treatment or alkali wash dispenses with two, :three or four water washings. The alternative above outlined will also serve to fix the tin or other metal used in any soluble form in the cellulose derivative.

The following examples are illustrations'of some of the methods which may be employed in practicing the applicants invention. Example 1.-One part of cellulose acetate artificial silk is treatedwithBO, parts of a stannic chloride solution (sp. gr. 1.?) for. one half hour at a temperature ranging from 40-130 50 C. The treated material is then removed from the stannic chloride oath, and the thus treated material is then rinsed off in water, the washing being continued until the washings give no test for any chlorine products. terial will be found to have increased substantially both in weight and volume, the tin, ap-

parently, having been fixed in the cellulose acetate as a stannic oxide, or as some other insoluble compound of tin.

Example 2.One part of cellulose acetate artificial silk istreated with 30 parts of a stannic chloride solution (sp. gr. 1.2) at a temperature ranging from to 55 degrees C. for one half hour. The cellulose acetate is then removed from the stannic chloride bath and washed with a very dilute solution of ammonia. The cellulose acetate is then Washed with water until the ammonia and all chlorine in soluble form is removed. A slightly greater increase in weight and volume was found after this treatment than was found in the treatment according to Example 1.

Example 3.--One part of cellulose propionate silk is treated with 30 parts of a stannic chloride solution (sp. gr. 1.2) for one half an hour at a After drying the mar temperature ranging from 45 to 65 degrees C. The cellulose propionate is then removed from the stannic chloride bath and washed with water and then with a very dilute solution of sodium carbonate for several minutes. It is then washed with water until the alkali and the chlorine in soluble form are removed. The material after swelling agent.

this treatment was found to have taken up a greater. percentage of the weighting material than in either of the previous examples.

The above examples are not to be considered limitative, as they merely indicate a few of the applications of the applicants process. Thus for instance other organic esters or ethers of cellulose can be used in place of the cellulose acetate and cellulose propionate mentioned in these examples. Also the stannic chloride can be replaced wholly or partially by other salts which have the property of weighting such cellulose derivatives, for example, zinc chloride, etc. In like manner the duration of the treatment with stannic chloride, etc. and the temperature employed can be varied in accordance with the results desired. The longer the treatment the greater will be the percentage of the weighting material taken up and the higher the temperature the greater the absorption of the weighting material. In raising the temperature of the stannic chloride bath care must be taken that this temperature is not raised to such a degree that the fiber or fabric is deteriorated.

The concentration of the stannic chloride, or other bath, can also be varied in accordance with the amount of weighting desired. However, where no independent jelling agent is employed the stannic chloride must be used in such concentration that it in itself will act as a jelling agent.

Where it is desired to use thestannic chloride or other weighting agent in such concentration that it in itself will not act as a jelling agent, the material which is being treated must be subjected to the action of an extraneous jelling or Where such a separate jelling agent is employed the same may be added to the stannic chloride or similar bath, or, if desired, the material to be treated may first be subjected to the action of the jelling agent and subsequently introduced into the stannic chloride or other weighting bath. Any known jelling or swelling agents for cellulose'esters or ethers such as formic acid, acetic acid, phenol, furfurol, pyridine, etc. may be used. The applicants have discovered that sulfocyanic acid or its isomer, or preferably, salts of these acids, can be used as swelling agents for such organic derivatives in connection with this process with excellent results.

From the above it will be seen that the process constituting this invention can be carried out either as a one-step process or as a two-step process. The invention also embraces within its scope processes wherein one agent is employed as both swelling agent and weighting agent and processes-where one or more agents are employed as swelling agents and another agent or other agents are employed as weighting agents.

While the process has been illustrated as applying to materials consisting wholly of organic derivatives of cellulose it is not to be considered as limited to such materials. It is applicable to yarns, fibers, fabrics, etc. whether the same consists wholly or partially of organic derivatives of cellulose. The steps set out in the various examples may be repeated one or more times when it isdesired to obtain a larger increase of volume and weight in the material treated.

In order to fix the metal in insoluble form in the material treated after the weighting treatment, water or very dilute aqueous solutions of any of the following may be used: Sodium carbonate, sodium bicarbonate, ammonia, sodium hydroxide, potassium hydroxide, droxide, etc.

Theterm metal compound in the form of an oxide used in the appended claims includes not only oxides of metals but also hydrated oxides of metals.

Having described our invention, what we claim and desire to secure by Letters Patent is:

1. A process of weighting material containing organic derivatives of cellulose which consists in treating said material with a solution which is a swelling agent for said cellulosic derivatives and contains a metal salt which is a weighting agent, then fixing the metal as an insoluble compound solely by washing the material with water and drying the material.

2. A process of weighting material containing organic derivatives of cellulosewhich consists in treating said material with a solution which calcium hyis a swelling agent for said cellulosic derivatives and contains a metal chloride which is a weighting agent, then fixing the metal as an insoluble compound solely by washing the materialwith water which is slightly alkaline due to the presence of compounds of the group consisting of solution of stannic chloride, then fixing the tin as an insoluble compound solely by washing the material with hard water and drying the material.

4. A process of weighting material containing organic derivatives of cellulose which consists in treating said material for one-half hour at 40 to 65 C. with a solution which is a swelling agent for said cellulosic derivatives and contains a metal salt which is a weighting agent, washing the material with water, thereby fixing a compound of the metal-in insoluble form in said material and drying the material.

5. A process of weighting material containing organic derivatives of cellulose which consists in treating said material for one half hour at to C. with a solution which is a swelling agent for said cellulosic derivatives and contains stannic chloride, washing the material with water which is slightly alkaline due to the presence of compounds 'of the group consisting of sodium carbonate, sodium bicarbonate, ammonia, sodium hydroxide, potassium hydroxide and calcium hydroxide, thereby fixing the tin as stannic oxide in said material and drying the material.

6. A process of treating material containing cellulose acetate which consists in treating saidcarbonate, sodium bicarbonate, ammonia, sodium hydroxide, potassium hydroxide and calcium hydroxide, and drying the material.

7. A process of weighting material containing cellulose acetate which consists in treating said material with a swelling agent for the cellulose acetate and then with a solution of stannic chloride, and then fixing the tin as an insoluble compound solely by washing the material with hard water and drying the material.

8. A process of weighting material containing cellulose acetate which consists in treating said material for one half hour at to C. with a solution which is a swelling agent for said cellulose acetate and contains stannic chloride, washing the material with water which is slightly alkaline due to the presence of compounds of the group consisting of sodium carbonate, sodium bicarbonate, ammonia, sodium hydroxide, potassium hydroxide and calcium hydroxide, thereby fixing the tin as stannic oxide in said cellulose acetate and drying the material.

9. A process of weighting material containing organic derivatives of cellulose which comprises treating said material with a solution of a suitable metallic salt which is of such concentration that at the temperature employed it acts as a swelling agent as well as a weighting agent for the said cellulosic derivatives and subsequently fixing the metal in the form of an insoluble compound solely by washing the thus treated material with water.

10. A'process of weighting material containing organic derivatives of cellulose which comprises treating said material with a solution of stannic chloride which is of such concentration that at the temperature employed it acts as a swelling agent as well as a weighting agent for the said cellulosic derivatives and subsequently fixing the tin in the form of an insoluble compound solely by washing the thus treated material with water.

11. A process of weighting material containing cellulose acetate which comprises treating said material with a solution of stannic chloride which is of such concentration that at the temperature employed it acts asa swelling agent as well as a weighting agent for the cellulose acetate and subsequently fixing the tin in the form of an insoluble compound solely by washing the thus treated material with water;

12. A process of weighting material containing cellulose acetate which comprises treating said material for one half hour at 45 to 55 C. with a solution of stannic chloride which is of such concentration that at the temperature employed it acts as a swelling agent as well as a weighting agent for the said cellulose acetate and subsequently fixing the tin in the form of stannic oxide solely by washing the thus treated material with hard water.

CAMILLE DREYFUS. HERBERT PLA'I'I'. 

